Bolt stop mechanism



NOV. 17, 1970 5, VARTANIAN EIAL 3,540,142

BOLT STOP MECHANISM Filed Sept. 25, 1968 2 Sheets-Sheet 1 INVENTORS. EDWIN s, VART'AN/AN WILLIAM J. B/LLETT I E. s. VARTANIAN ETAL 3,540,142

Nov. 17, 1970- sour STOP MECHANISM 2 Sheets-Sheet 2 Filed Sept. 25, 71968 INVENTORS' EDWIN S. VARTAN/AN WILLIAM J BILL ETT BY a) 6.. #2 J ATTORNEY United States Patent Ofiiice 3,540,142 Patented Nov. 17, 1970 US. Cl. 432-22 6 Claims ABSTRACT OF THE DISCLOSURE A stop mechanism for automatically retaining a firearm bolt in its retired position after the last round in a gun is fired, which bolt stop is also manually actuable at any time the bolt is moved to its retired position, and which bolt stop is manually releasable.

This invent-ion relates to a bolt stop mechanism for a semi-automatic firearm which bolt stop is automatically actuated to retain the bolt in its retired position after the last round in the gun is fired. The bolt stop mechanism of his invention is manually releasable, and furthermore, may be manually actuated to retain the bolt at any time the latter is moved to the retired position.

It is known to provide a mechanism in a bolt action firearm for retaining the bolt in its retired position. The bolt stops of the prior art are of two general types, those which automatically retain the bolt in its retired position after the last round in the magazine is fired, and those which are manually actuable at any time once the bolt is moved to its retired position. The automatically operated bolt stops of the prior art have proved to be unsatisfactory because of extreme sensitivity to accidental jarring of the firearm stock which may occur after the bolt has been stopped in its retired position, such jarring generally re sulting in the bolts being unlocked and driven to its battery position. A further disadvantage attendant to the automatic variety of prior art bolt stops resides in their inability to retain the bolt in its retired position once the magazine is removed from the gun. Yet another disadvantage of the prior art automatic bolt stops is that they are not manually operable to retain the bolt at any time that the shooter desires. The manually operable bolt stops of the prior art are undesirable because they do not function automatically after the last round in the gun is fired, and thus to operate this type of known bolt stop, the shoot er must first manually move the bolt to its reired position.

This invention is directed toward a bolt stop assembly which is both manually and automatically operable, and which provides all of the advantages of both types of prior art bolt stops without any of the attendant disadvantages. The bolt stop assembly of this invention operates automatically to lock the bolt in the retired position after the last round in the gun is fired, and the bolt remains locked when the cartridge magazine is removed from the receiver. The bolt stop of this invention will not release the bolt if the gun stock is accidently jarred, but the bolt can be released by a simple manual manipulation. Furthermore, the bolt stop assembly of this invention can be manually actuated at any time the bolt is moved to the retired position, thus the shooter may lock the bolt in its retired position at any time he chooses. Still further the bolt may be manually released with rounds in the magazine, with empty magazine, or with magazine removed from the gun.

The bolt stop assembly of this invention includes a bolt stop member pivotally mounted in the firearm receiver, which bolt stop member is movable into and out of engagement with the bolt. The bolt stop is normally disposed out of engagement with the bolt. The bolt stop includes a portion which is contacted by a spring-biased cartridge follower in the cartridge magazine after the last round in the magazine has been chambered in the firearm. The cartridge follower urges the bolt stop into engagement with the bolt when the latter is driven to its retired position after the last round has been fired. A latch and release member is movably mounted in the receiver and is automatically moved into latching engagement with the bolt stop when the latter engages the bolt. The latch and. release member serves to support and positively lock the bolt stop against the bolt. The latch and release member can be manually moved out of engagement with the bolt stop so as to permit the latter to move out of engagement with the bolt. When one or more cartridges are disposed within the magazine, the cartridge follower does not contact the bolt stop so as to urge the latter into engagement with the bolt, but the latch and release member can be manually operaed to move the bolt stop against the bolt at any time that the bolt is moved to its retired position. Furthermore, a connection between the firearm hammer and the bolt stop member is preferably provided, which connection prevents the bolt stop from engaging the bolt except When the hammer is cocked.

Thus, it is an object of this invention to provide a bolt stop assembly for semi-automatic firearms, which bolt stop assembly is automatically operable to lock the bolt in its retired position after the last round in the firearm has been fired.

It is a further object of this invention to provide a bolt stop assembly of the character described which is manually operable to lock the bolt in its retired position at any time when the bolt has been moved to such retired posi tion.

It is yet another object of this invention to provide a bolt stop assembly of the character described wihch will not release the bolt when the firearm stock is accidently jarred, and yet will release the bolt after a simple manual manipulation even with rounds in the magazine, an empty magazine, or with the magazine removed from the gun.

It is still another object of this invention to provide a bolt stop mechanism of the character described which is easily assembled, of inexpensive manufacture, and durable under heavy use.

Other objects, features, and advantages of this invention will become apparent to one skilled in the art from the following detailed description and accompanying drawings, in which:

FIG. 1 is an exploded view in perspective of the various components of a preferred embodiment of the bolt stop assembly of this invention,

FIG. 2 is a side view partially in section of the receiver portion of a firearm containing the bolt stop assembly of FIG. 1, with the firearm hammer being shown in a position immediately prior to firing the last round in the gun;

FIG. 3 is a side view similar to FIG. 2, but showing the bolt in its retired position and held therein by the bolt stop;

FIG. 4 is a sectional view taken along line 44 in FIG. 2, showing details of the latch and release member; and

FIG. 5 is a sectional view taken along line 55 in FIG. 3, showing the latch and release member in engagement with the bolt stop to lock the latter in engagement with the bolt.

Referring now to FIG. 1, the preferred embodiment of the bolt stop assembly of this invention includes a bolt stop member 2 which is pivotally mounted on a pin 4. The bolt stop 2 includes an inclined surface 6 which may be moved into engagement with a complementary surface 8 on the bolt 10. A spring 12 engages the bolt stop 2 to bias the latter in a clockwise direction about the pin 4. The bolt stop 2 includes an elongated forward portion 14 which engages the cartridge follower 16 in the cartridge magazine 18 in a manner described in greater detail hereinafter. It is noted that the cartridge follower 16 ex tends rearwardly beyond the back face of a cartridge 20 disposed in the magazine 18, so that the cartridges 20 do not contact the portion 14 of the bolt stop 2 as the cartridges 20 are fed from the magazine 18. A latch and release member 22 extends laterally of the bolt stop 2, the latch and release member including a notch 24 having an inclined cam surface 26 adjacent to an upwardly extending shoulder 28. The latch and release member 22 includes a stem portion 30 of reduced diameter about which is mounted a spring 32. The stem 30 defines flange 34 against which the spring 32 bears. The stem 30 further includes an undercut portion 36 in which is disposed a notch 38 cut into a stop member 40. The stop member 40 is mounted on a pin 42 and provides a surface against which the other end of the spring 32 is set, and further controls the extent of movement of the latch and release 22 by providing a surface against which the sides of the undercut portion 36 are driven. The bolt stop 2 includes an indentation 44 which engages either the latch and release notch 24 or shoulder 28, as will be described in greater detail hereinafter.

A firearm hammer 46 is pivotally mounted on a dowel 48, the hammer 46 including a laterally extending pin 50 which extends into the confines of a slot 52 cut into the bolt stop 2. It is noted that the rearward portion of the slot 52 includes a vertically directed segment 54.

Referring now to FIG. 2 the bolt 10 is shown in a firearm receiver in its battery position with the last cartridge 20 in the gun being chambered for firing. With the last cartridge 20 having been removed from the magazine 18, the cartridge follower 16 is biased upwardly by the spring 17 and against the forward portion 14 of the bolt stop 2. The cartridge follower 16 thus tends to pivot the bolt stop 2 about the pin 4 and against the bias of the spring 12. The bolt 10, being in the battery position, however, prevents the bolt stop from pivoting in the counter-clockwise direction, and the bolt stop 2 remains in an inoperative position. It is noted that when the bolt stop 2 is in the inoperative position shown in FIG. 2, the indentation 44 is disposed in the latch and release notch 24 (see FIG. 4).

After the cartridge 20 is fired, the bolt 10 is moved to a rearward retired position by means of a pair of slide arms 11 (only one of which is shown) and any conventional gas system (not shown), as shown in FIG. 3. When the bolt 10 is in its retired position, the bolt stop 2 is free to pivot in a counterclockwise-direction under the influence of the spring-biased cartridge follower 16. Movement of the bolt 10 to the retired position causes the hammer 46 to pivot to a cocked position thus moving the pin 50 into the vertical segment 54 of the bolt stop slot 52. As the bolt stop 2 pivots in a counter-clockwise direction, the inclined surface 6 is moved into the path of the bolt 10 and the shoulder 28 on the latch and release 22 is moved under the bolt stop indentation 44 to support and lock the bolt stop in the position shown in FIG. 3. The complementary surface 8 on the bolt 10 is then moved against the bolt stop surface 6 and the bolt is held in its retired position.

FIGS. 4 and show the operation of the latch and release member 22 of the assembly of this invention. In FIG. 4 the bolt stop indentation 44 is shown disposed in the latch and release notch 24 adjacent to the cam surface 26. The spring 32 is operative to urge the cam surface 26 toward the bolt stop but the spring constant is such that the force of the spring 32 alone is not sufficient to move the indentation 44 across the cam surface 26.

When the bolt stop 2 is moved to the position shown in FIG. 3 in the manner previously described, the indentation 44 is lifted out of the notch 24 and the spring 32 automatically moves the latch and release to the left (as shown in FIGS. 4 and 5) so that the shoulder 28 is moved under the indentation 44, as shown in FIG. 5. The shoulder 28 thus serves to lock the bolt stop 2 in the position shown in FIG. 3. It is readily apparent that the bolt stop 2 will not move if the stock of the firearm is accidently jarred causing the bolt 10 to move slightly rearwardly.

The bolt stop 2 can be manually released from the bolt 10 by pushing the left hand end 58 of the latch and release 22 (as shown in FIGS. 4 andS) so as to move the latter to the right and slide the shoulder 28 out from under the indentation 44. By thus removing the support a for the bolt stop 2, the indentation 44 will be returned to the notch 24 by the force of the bolt 10 as the latter is urged toward its battery position by conventional spring means (not shown).

If one desires to manually lock the bolt 10 in the retired position at any time prior to firing the last round in the magazine, or at any time when no magazine is in the gun, one need merely manually move the bolt to the retired position and push the right hand end 60 of the latch and release 22 to the left (as shown in FIGS. 4 and 5) thereby causing the indentation 44 to move up the cam surface 26 and onto the shoulder 28. Manual release of the bolt can then be accomplished in the manner described above.

It is thus readily apparent that the bolt stop mechanism of this invention provides for both automatic and manually operable retention of the bolt in the retired position, and further permits manual release of the bolt. The bolt stop mechanism of this invention is of superior stability and durability, with relatively simple construction.

Since many changes and variations of the disclosed embodiment of the invention may be made without departing from the inventive concept, it is not intended to limit the invention otherwise than as required by the appended claims.

What is claimed is:

1. In a semi-automatic firearm having a reciprocating bolt and adapted for use with an ammunition magazine having a spring-biased cartridge follower, a bolt stop mechanism comprising:

(a) bolt stop means mounted on said firearm and movable in a first direction into a bolt-engaging position when said bolt is in a retired position; and

(b) latch and release means mounted in said firearm for movement in a second direction substantially normal to said first direction into supporting engagement with said bolt stop means when the latter is in the bolt-engaging position to lock said bolt stop means in said position, said latch and release means being held substantially immobile by the firearm with respect to movement in said first direction.

2. The bolt stop mechanism of claim 1, wherein said bolt stop means contacts said cartridge follower when said magazine is devoid of cartridges and said cartridge follower serves to move said bolt stop means into said bolt-engaging position after a last cartridge is fired from said firearm.

3. The bolt stop mechanism of claim 1, further comprising spring means operative to automatically move said latch and release means into supporting engagement with said bolt stop means after the latter is moved to said boltengaging position.

4. The bolt stop mechanism of claim 1, further comprising cam means on said latch and release means, said cam means being adjacent to said bolt stop means and said cam means being operative to cam said bolt stop means into said bolt-engaging position upon manual movement of said latch and release means when said bolt is in said retired position.

5. In a semi-automatic firearm having a reciprocating bolt and adapted for use with an ammunition magazine having a spring-biased cartridge follower, a bolt stop mechanism comprising:

(a) bolt stop means mounted on said firearm and adapted to contact said cartridge follower when said magazine is devoid of cartridges, said bolt stop means being movable from a position out of engagement with the bolt in a first direction into a bolt-engaging position;

(b) latch and release means mounted on said firearm for movement in a second direction lateral to said first direction, said latch and release means having a notch normally aligned with said bolt stop means to permit the latter to be positioned out of engagement with the bolt, and a raised shoulder adjacent said notch, movement of said latch and release means in said second direction being operative to move said raised shoulder into supporting engagement with said 5 bolt stop means when the latter is in said bolt-engaging position to lock said bolt stop means in said boltengaging position, said latch and release means being substantially immoblized by the firearm against movement in said first direction; and

(c) spring means operative to urge said latch and release means in said second direction.

6. The bolt stop mechanism of claim 5, further comprising cam means on said latch and release means, said cam means being disposed adjacent said bolt stop means and manually movable against said bolt stop means to cam the latter into said bolt-engaging position when said bolt is in its retired position.

References Cited UNITED STATES PATENTS 1,349,345 8/1920 Payne 42-18 1,533,966 4/1925 Browning 4218 3,098,311 7/1963 Savioli 42-48 BENJAMIN A. BORCHELT, Primary Examiner C. T. JORDAN, Assistant Examiner US. Cl. X.R. 42-18 

